Mercurial > vim
view src/logfile.c @ 34394:a400c8f9506f v9.1.0123
patch 9.1.0123: MS-Windows: system() may deadlock
Commit: https://github.com/vim/vim/commit/52ecc76c7fa1865603f27bc838efaeaa03cad77c
Author: GuyBrush <miguel.barro@live.com>
Date: Wed Feb 21 20:16:38 2024 +0100
patch 9.1.0123: MS-Windows: system() may deadlock
Problem: MS-Windows: system() may deadlock when calling binaries that
expect stdin
Solution: Ignore the SHELL_EXPAND flag
(GuyBrush)
This happens on binaries that expect stdin. For example:
:echo system("xxd")
will cause a deadlock.
SHELL_EXPAND is a flag devoted to support the linux implementation of
the backtick-expansion mechanism.
On linux backtic-expansion relies in the function mch_expand_wildchars()
(os_unix.c) that delegates on each specific shell (bash, sh, csh, zsh)
the expansion. Basically it composes a shell command that does the
expansion and redirects the output to a file and call_shell() it. On
windows backtick-expansion is performed by Vim itself.
On linux SHELL_EXPAND modifies how mch_call_shell_fork() (os_unix.c)
works. This function:
- relies on posix fork() to spawn a child process to execute a
external command.
- Child and parent process communicate using pipes (or pseudoterminal
if available).
User input (type ahead content) is processed in a loop only if
!(SHELL_EXPAND || SHELL_COOKED).
Though signals are used to detect Ctrl-C in all cases (the input
loop is not necessary to interrupt the function).
In the backtick-expansion the external command is the shell command
that provides the expansion. For the child redirection:
- SHELL_EXPAND replaces stdin, stdout & stderr to /dev/null. This is
why the shell command composed includes redirection (otherwise
output would be lost).
- !SHELL_EXPAND replaces stdin, stdout & stderr with the parent
created pipes (or pseudoterminal).
Note that the use of SIGINT signal prevents mch_call_shell_fork()
from hanging vim.
On Windows mch_system_piped() (os_win32.c) (which is only used when the
GUI is running) mimics mch_call_shell_fork() (os_unix.c).
Win32 lacks fork() and relies on CreateProcessW() and only has pipe
support (not pseudoterminal) which makes the implementation much
different.
But, the key idea is that windows lacks signals, the OS provides support
for console apps but gvim is not one. The only way of detecting a Ctrl-C
is actually processing user input (type ahead content). By ignoring the
user input under SHELL_EXPAND the function can hang gvim.
Ignoring SHELL_EXPAND flag has no consequence in Windows because as
mentioned above it is only meaningful in linux.
closes: #13988
Signed-off-by: GuyBrush <miguel.barro@live.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
author | Christian Brabandt <cb@256bit.org> |
---|---|
date | Wed, 21 Feb 2024 20:30:02 +0100 |
parents | 533e36e02a68 |
children |
line wrap: on
line source
/* vi:set ts=8 sts=4 sw=4 noet: * * VIM - Vi IMproved by Bram Moolenaar * * Do ":help uganda" in Vim to read copying and usage conditions. * Do ":help credits" in Vim to see a list of people who contributed. */ /* * Implements logging. Originally intended for the channel feature, which is * why the "ch_" prefix is used. Also useful for any kind of low-level and * async debugging. */ #include "vim.h" #if defined(FEAT_EVAL) || defined(PROTO) // Log file opened with ch_logfile(). static FILE *log_fd = NULL; static char_u *log_name = NULL; #ifdef FEAT_RELTIME static proftime_T log_start; #endif void ch_logfile(char_u *fname, char_u *opt) { FILE *file = NULL; char *mode = "a"; if (log_fd != NULL) { if (*fname != NUL) ch_log(NULL, "closing this logfile, opening %s", fname); else ch_log(NULL, "closing logfile %s", log_name); fclose(log_fd); } // The "a" flag overrules the "w" flag. if (vim_strchr(opt, 'a') == NULL && vim_strchr(opt, 'w') != NULL) mode = "w"; ch_log_output = vim_strchr(opt, 'o') != NULL ? LOG_ALWAYS : FALSE; if (*fname != NUL) { file = fopen((char *)fname, mode); if (file == NULL) { semsg(_(e_cant_open_file_str), fname); return; } vim_free(log_name); log_name = vim_strsave(fname); } log_fd = file; if (log_fd != NULL) { fprintf(log_fd, "==== start log session %s ====\n", get_ctime(time(NULL), FALSE)); // flush now, if fork/exec follows it could be written twice fflush(log_fd); #ifdef FEAT_RELTIME profile_start(&log_start); #endif } } int ch_log_active(void) { return log_fd != NULL; } static void ch_log_lead(const char *what, channel_T *ch UNUSED, ch_part_T part UNUSED) { if (log_fd == NULL) return; #ifdef FEAT_RELTIME proftime_T log_now; profile_start(&log_now); profile_sub(&log_now, &log_start); fprintf(log_fd, "%s ", profile_msg(&log_now)); #endif #ifdef FEAT_JOB_CHANNEL if (ch != NULL) { if (part < PART_COUNT) fprintf(log_fd, "%son %d(%s): ", what, ch->ch_id, ch_part_names[part]); else fprintf(log_fd, "%son %d: ", what, ch->ch_id); } else #endif fprintf(log_fd, "%s: ", what); } #ifndef PROTO // prototype is in proto.h void ch_log(channel_T *ch, const char *fmt, ...) { if (log_fd == NULL) return; va_list ap; ch_log_lead("", ch, PART_COUNT); va_start(ap, fmt); vfprintf(log_fd, fmt, ap); va_end(ap); fputc('\n', log_fd); fflush(log_fd); did_repeated_msg = 0; } void ch_error(channel_T *ch, const char *fmt, ...) { if (log_fd == NULL) return; va_list ap; ch_log_lead("ERR ", ch, PART_COUNT); va_start(ap, fmt); vfprintf(log_fd, fmt, ap); va_end(ap); fputc('\n', log_fd); fflush(log_fd); did_repeated_msg = 0; } #endif #if defined(FEAT_JOB_CHANNEL) || defined(PROTO) /* * Log a message "buf[len]" for channel "ch" part "part". * Only to be called when ch_log_active() returns TRUE. */ void ch_log_literal( char *lead, channel_T *ch, ch_part_T part, char_u *buf, int len) { ch_log_lead(lead, ch, part); fprintf(log_fd, "'"); vim_ignored = (int)fwrite(buf, len, 1, log_fd); fprintf(log_fd, "'\n"); fflush(log_fd); } #endif /* * "ch_log()" function */ void f_ch_log(typval_T *argvars, typval_T *rettv UNUSED) { char_u *msg; channel_T *channel = NULL; if (in_vim9script() && (check_for_string_arg(argvars, 0) == FAIL || check_for_opt_chan_or_job_arg(argvars, 1) == FAIL)) return; msg = tv_get_string(&argvars[0]); #if defined(FEAT_JOB_CHANNEL) if (argvars[1].v_type != VAR_UNKNOWN) channel = get_channel_arg(&argvars[1], FALSE, FALSE, 0); #endif // Prepend "ch_log()" to make it easier to find these entries in the // logfile. ch_log(channel, "ch_log(): %s", msg); } /* * "ch_logfile()" function */ void f_ch_logfile(typval_T *argvars, typval_T *rettv UNUSED) { char_u *fname; char_u *opt = (char_u *)""; char_u buf[NUMBUFLEN]; // Don't open a file in restricted mode. if (check_restricted() || check_secure()) return; if (in_vim9script() && (check_for_string_arg(argvars, 0) == FAIL || check_for_opt_string_arg(argvars, 1) == FAIL)) return; fname = tv_get_string(&argvars[0]); if (argvars[1].v_type == VAR_STRING) opt = tv_get_string_buf(&argvars[1], buf); ch_logfile(fname, opt); } #endif // FEAT_EVAL